1. Field of the Invention.
The present invention relates to a chair comprising a support structure and a seat connected to the support structure by means of an adjustable parallelogram system that includes members in the form of levers. The first ends of the levers are hinged to the seat, and the second ends of the levers are hinged to the support structure such that the seat is able to move between a lowered position and a raised position. A backrest is hinged to the support structure and is operationally connected to the seat so as to be able to pivot between an upright position corresponding to the lowered position of the seat and a reclined position corresponding to the raised position of the seat.
2. Description of the Prior Art
French Pat. No. 2,045,120 discloses a chair having a parallelogram system for pivotally supporting a seat on a support structure. The backrest is pivoted to the support structure by a lever that is not part of the seat supporting parallelogram system. Reclining the backrest causes the lever to force the back edge of the seat upwardly and backwardly relative to the support structure. The chair of the aforementioned patent allows the backrest to exert on the back of the user a force proportional to his weight. However, the structure of the chair of the French patent is somewhat complicated. Moreover, the design of the adjustable parallelogram system associated with the mechanism for controlling displacement of the seat by the backrest requires excessive space.